simplifying linux_emul_convpath()

[Don Lewis]

On 14 Jan, Robert Watson wrote:

> ino_t probably does need to get bumped to 64-bit on FreeBSD at some point,
> because at some point we will have a local file system that can usefully
> represent more than 2 billion files.  I assume we didn't do the bump with
> UFS2 because of the potential disruption for applications, etc.

We'd have a heck of a time fsck'ing such a file system on a 32 bit
machine.